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Parallel-connected modules have been widely used in battery packs for electric vehicles nowadays. Unlike series-connected modules, the direct state inconsistency caused by parameter inconsistency in parallel modules is current and temperature non-uniformity, thus resulting in the inconsistency in the speed of aging among cells. Consequently, the evolution pattern of parameter inconsistency is different from that of series-connected modules. Since it’s practically impossible to monitor each cell’s current and temperature information in battery packs, considering cost and energy efficiency, it’s necessary to study how the parameter inconsistency evolves in parallel modules considering the initial parameter distribution, topology design and working condition. In this study, we assigned cells of 18650 format into several groups regarding the degree of capacity and resistance inconsistency. Then all groups are cycled under different environmental temperature and current profile.

Fuel cells directly convert the energy stored in hydrogen into electrical energy through an electrochemical reaction, and the only reaction product is water, which can improve the energy efficiency and reduce the pollution caused by fossil fuels. The fuel cell hybrid power system used in vehicles usually consists of a fuel cell stack and a power battery module, and the DC/DC converter is the key component to connect them together. The current ripples caused by the system have been confirmed to have detrimental effects on the fuel cell’s reliability and lifespan. In addition, it is one of the key factors that reduce the system efficiency. So, it is necessary to analyze the current ripple in the system and maintain it at a low level. In this paper, a brief review on the different kinds of converters used in vehicles has been made. Then, with the help of MATLAB/SIMULINK, a simulation model of the hybrid power system based on 4-phase interleaved parallel topology is established.

The application of Li(Ni0.8Co0.1Mn0.1)O2 (NCM811) cathode-based lithium-ion batteries (LIBs) has alleviated electric vehicle range anxiety. However, the subsequent thermal safety issues limit their market acceptance. A detailed analysis of the failure evolution process for large-format LIBs is necessary to address the thermal safety issue. In this study, prismatic cells with nominal capacities of 144Ah and 125Ah are used to investigate the thermal runaway (TR) characteristics triggered by lateral overheating. Additionally, TR characteristics under two states of charge (SoCs) (100% and 5%) are discussed. Two cells with 100% SoC exhibit similar characteristics, including high failure temperature, high inhomogeneity of temperature distribution, multi-points jet fire, and significant mass loss. Two cells with 5% SoC demonstrate only a slight rupture of the safety valve and the emission of white smoke.